1. Field of the Invention
This invention relates to methods and apparatus for enhancing the production of oil and gas wells, specifically those in which rock formations surrounding the well are fractured to release entrapped oil or gas.
2. Brief Description of the Prior Art
The ever increasing requirements in our modern society for fossil fuel products has spurred the development of numerous techniques and apparatus for maximizing the production of subterranean wells. Perhaps the most popular of these techniques is the injection of water or steam into one or more secondary wells surrounding a primary well such that the injected fluid forces the oil or gas towards the primary well.
Although these techniques have proven generally successful, they have not proven adequate to economically remove oil or gas entrapped in a rock formation adjacent a primary well. To remove such entrapped fuel, the prior art techniques have involved many methods of fracturing the rock formation. One such technique involves the injection of an hydraulic fluid either through the main well or an adjacent, secondary well at an increasing pressure until the rock formation reaches its fracturing point. This technique, however, does not provide any control over the amount or direction of fracturing, since, quite obviously, the rock formation will fracture at its weakest point.
Other techniques involve the application of electrical or infra-red energy to the rock formation which causes the fluids entrapped therein to vaporize, thereby increasing the pressure in the formation. When sufficient internal pressure has been generated, the rock formation will fracture. When electrical energy is applied to the rock formation, a plurality of electrodes are disposed in adjacent wells and high energy continuously applied, short duration electrical pulses may be passed between them. These systems generally require a large power input making them uneconomical to use except in those wells where large amounts of unrecovered fuels exist.